Layman's abstract: Women with a history of preeclampsia in pregnancy are at reduced risk of breast cancer, especially those who delivered a son, not a daughter, from the pregnancy. Why is this so? We compare hormones in the blood of a group of women who had been diagnosed with preeclampsia in pregnancy to hormones in a group who had normal pregnancies, after taking into consideration their age and other factors that influence hormone levels. We hypothesize that women with a history of preeclampsia will have lower estrogens and growth factors related to breast cancer than women who had normal pregnancies.